Liquid thermal diffusion port design



J1me 1956 w. E. SCOVILL 2,752,042

LIQUID THERMAL DIFFUSION PORT DESIGN Filed Aug. 27, 1953 V 2 SheetsShcet1 INVENTOR. q- E WfiRNE/Z E. 5cov/LL A TTORNE vs June 26, 1956 w. E.SCOVILL 2,752,042

LIQUID THERMAL DIFFUSION PORT DESIGN Filed Aug. 27, 1953 2 Sheets-Sheet2 i -C- 55" y 57 IAIIIIIIIIIIIIIIIII.

IIII'IIII YIIIIIIIIIII INVENTOR. WqR/vm E. Scowu.

BY W,Wamm

United States Patent Office 2,752,042 Patented June 26, 1956 LIQUIDTHERMAL DIFFUSION PORT DESIGN Warner E. Scovill, Lakewood, Ohio,assignor to I he Standard Oil Company, Cleveland, Ohio, a corporation ofOhio Application August 27, 1953, Serial No. 376,927

3 Claims. (Cl. 210-525) The present invention relates to continuousthermal difiusion apparatus for separating fluid mixtures and, moreparticularly, to novel and improved apparatus for improving the flow offluid mixtures in apparatuses of this type.

One type of thermal diffusion apparatus that has been proposed in recentyears for the purpose of resolving fluid mixtures into two or moredissimilar fractions has consisted essentially of two stationary smoothwalls of inert, heat conductive materials spaced relatively close to oneanother to form a separation chamber, referred to generally as a slit.In this type of thermal difiusion apparatus, inlets and outlets areprovided, usually in the walls, for the continuous introduction of fluidinto the separation chamber and the continuous withdrawal therefrom oftwo or more separated fractions.

One of the major problems in systems of this type involves thedistribution of fluid flow through the slit. Previous experimentation insystems of this type indicates .that one of the primary causes of poorresults achieved in the separation of fluid mixtures by thermaldiflusion is caused primarily by poor distribution of fluid flow throughthe slit. For example, upon dismantling a thermal difiusion column ofthe center feed, countercurrent flow, vertical flat plate type, when thelength of the slit was 5 ft., the breadth about 2 ft., and the slitwidth about 0.035 in., and wherein the liquid measure was introducedinto the slit through a line of small holes in the surface of one of theplates, the holes being spaced about of an inch apart, and thedissimilar fractions were withdrawn through ports of identicalconstruction located opposite ends of the slit, the surprising discoverywas made that the surface of the hot wall between the inlet port and thewithdrawal port at the top of the slit showed a series of very sharp,parallel and colored lines, each connecting one particular hole of theinlet port with one particular hole of the withdrawal port. A similarseries of lines were found on the cold wall between the inlet port andthe other withdrawal port indicating that the flow was not distributedover the breadth of the slit but was more or less direct between theholes. This indicated that although the efliciency of the column wasalready considerably higher than had heretofore been believed possible,apparently only a fraction of the breadth of the slit was being usedeffectively in the process.

It is an object of the invention, accordingly, to provide novel andimproved apparatus for controlling the flow of fluid through a thermaldiffusion column, in order to overcome the aforementioned disadvantages.

In accordance with the invention, it has now been found that it ispossible to overcome this defect by providing liquid thermal diffusionapparatus with inlet and withdrawal ports at least one of which,preferably at least the inlet port, comprises an elongated groove in theface of the wall forming a reservoir, a passageway for liquid extendingfrom and substantially co-extensive with the breadth of the groove andcommunicating with the groove and the slit formed between the thermaldiffusion plates, and a conduit communicating with the groove to theexterior of the apparatus. To promote movement of the liquid between theinlet and withdrawal ports in the form of continuous films rather thanin a series of parallel streams, the volumetric capacity of thereservoir forming part of each, or at least one, of the ports,constructed in accordance with the invention, is large in relation tothe volumetric flow capacity of the passage from the reservoir to theslit. To assure substantially uniform flow from the reservoir into theslit, the pressure drop between the reservoir and the slit will be largeas compared with the diflerence in pressure across the passageway alongthe breadth of the reservoir. Therefore, the flow of fluid across thepassageway is expected to be substantially uniform along its entirebreadth. This results in an increase in the efliciency of separationobtainable in a thermal diffusion apparatus of given dimensions.

For a more complete understanding of the invention, reference should behad to the following detailed description of an exemplary embodiment ofthe invention taken in conjunction with the figures of the drawing, inwhich:

Fig. 1 is a perspective view in cross-section of a novel and improvedport design for thermal diffusion apparatus, in accordance with theinvention;

Fig. 2 is a view in vertical section, taken along the line 22 in thedirection of the arrows, of the apparatus of Fig. l; and

Fig. 3 is a cross-sectional view in elevation of a thermal diffusionapparatus provided with the improved port design of the invention.

In Figs. 1 and 2, there are shown two thermal diffusion plates 11 and12, which are separated by a gasket 13 and spaced apart by a distanceless than about 0.15 in. The wall 11 is provided with an elongatedgroove 14 forming a reservoir. The groove 14 is connected by a conduit15 to a suitable source of feed or a receptacle for the product,externally positioned with relation to the thermal diffusion plates 11and 12. A ledge 16 is formed along 'the line of the elongated groove 14and is positioned in "such a manner with respect to the walls 17 and 19of the plates 11 and 12 as to form a restricted passageway leading fromthe elongated groove 14 to a thermal diffusion slit 18 formed by theplates 11 and 12.

In order to more clearly understand the functioning of the improved portconstruction, in accordance with the invention, let us consider theillustrated port as an inlet port to the thermal diffusion slit 18. Feedwill be forced under pressure at a predetermined rate of flow throughthe conduit 15 from a suitable source of feed (not shown) into theelongated groove 14, which acts as a reservoir. It will be obvious tothose skilled in the art that the pressure at points spaced along thelength of the elongated groove 14 at varying distances from the conduit15 will have values differing in proportion to their respectivedistances from the conduit 15.

The feed from the reservoir formed by the elongated groove 14 must flowin the restricted passageway formed by the ledge 16 and the wall 17 ofthe plate 12 in order to reach the slit 18. The pressure drop betweenthe reservoir 14 and the slit 18 will be large as compared with thedifference in pressure along the breadth of the reservoir 14.

Thus, there is provided a novel and improved port construction, whereinthe flow of fluid between the slit formed by the thermal diffusionplates and a port communicating with the slit is substantially uniformalong the entire breadth of the connection between the port and theslit.

The apparatus illustrated in Fig. 3 comprises two opposed walls 20 and21 forming between them a separation chamber or thermal diffusion slit22. At the lower end of the apparatus there is a groove 24 in the wall21 which is coextensive with the face of that wall and lies in adirection transverse to the vertical direction of flow of on eitherplate.

liquid within the slit 22. A passage 26 for liquid is connected with thegroove 24 and communicates with the exterior of the apparatus. The wall21 is provided with a ledge 27 that is coextensive with the groove 24and is positioned between the slit 22 and the groove 24 to form with thewall 20 a restricted passageway between; the slit 22andthegroove24. Y V

The port construction illustrated in the-upper portion of Fig. '3is'essentially similar except that the ledge 27a is in the wall 20rather than the wall 21. The apparatus is appropriately sealed by meansof gaskets 29. Intermediate the upper and lower ports there is an inletport comprising a groove 30, passage 31 for communication to theexterior, and ledges 32 and 33. a

In operation, the wall 21 may, for example, be heated and the wall 20may be maintained at a relatively lower perature by means of a suitableheating medium, the fraction tending to accumulate adjacent the hot wallwill ascend along said wall, flow past the ledge 27a, be collected inthe groove 24a and withdrawn through passage 26a, whereas the fractiontending to accumulate adjacent the cold wall 20 will descend, flow pastthe ledge 27, be collected in groove 24 and withdrawn through passage26. I a a a It will be obvious that the above-disclosed embodiments aremeant to be merely exemplary and are susceptible of modification andvariation without departing from the spirit and scope of the invention.For example, the ledge 16 will perform its function equally wellregardless of whether the disclosed structural configuration is utilizedas an inlet or as a withdrawal port, or whether it is 40 formedintegrally or separately from the plates or formed Therefore, it isdeemed that the invention is not to'be limited except by the appendedclaims.

I claim:

1. Liquid thermal diffusion apparatus comprising two substantiallyparallel, liquid-impervious stationary walls, the opposed faces of whichare smooth and spaced apart to form a substantially uniform narrowthermal diffusion slit, means providing ports communicating with theslit through which the liquid is introduced into and withdrawn from saidslit, at least one of said ports including an elongated groovelongitudinally disposed adjacent said slit and in the face of one ofsaid walls, a passage for liquid connected with said elongated grooveand communicating with the exterior ofthe apparatus, .aledge in one ofsaid walls running along the breadth of said elongated groove andpositioned between said slit and said elongated groove and in suchcontiguous relationship with theother of said two stationary walls so asto form a restricted passageway between said elongated groove and saidslit.

2. The apparatus described in claim 1, wherein said ledge is integralwith said one of said walls' having said elongated groove therein. r g Ip,

'3. Liquid thermal difiusion apparatus comprising two liquid imperviouswalls, the opposed faces of which are substantially equidistantly spacedapart to form a narrow thermal diffusion slit, and means providing portscommunicating with the slit for introducing and withdrawing liquid intoand from the slit, respectively, whereinat least one of said portsincludes a groove in the face of one of the walls, said groove beingsubstantially coextensive with said face and in a direction transverseto the direction of flow of liquid within the slit, a passage for liquidconnected with said groove and communicating with the exterior of theapparatus, a ledge in one of said Walls coextensive with said groove andpositioned between said slit and said groove and in such contiguousrelationship with the other of said walls so as to form a restrictedpassageway between said elongated groove and said slit.

References Cited in the file of this patent UNITED STATES PATENTS DebyeSept. 11, 1951

1. LIQUID THERMAL DIFFUSION APPARATUS COMPRISING TWO SUBSTANTIALLYPARALLEL, LIQUID-IMPERVIOUS STATIONARY WALLS, THE OPPOSED FACES OF WHICHARE SMOOTH AND SPACED APART TO FORM A SUBSTANTIALLY UNIFORM NARROWTHERMAL DIFFUSION SLIT, MEANS PROVIDING PORTS COMMUNICATING WITH THESLIT THROUGH WHICH THE LIQUID IS INTRODUCES INTO AND WITHDRAWN FROM SAIDSLIT, AT LEAST ONE OF SAID PORTS INCLUDING AN ELONGATED GROOVELONGITUDINALLY DISPOSED ADJACENT SAID SLIT AND IN THE FACE OF ONE OFSAID WALLS, A PASSAGE FOR LIQUID CONNECTED WITH SAID ELONGATED GROOVEAND COMMUNICATING WITH THE EXTERIOR OF THE APPARATUS, A LEDGE IN ONE OFSAID WALLS RUNNING ALONG THE BREADTH OF SAID ELONGATED GROOVE ANDPOSITIONED BETWEEN SAID SLIT AND SAID ELONGATED GROOVE AND IN SUCHCONTIGUOUS RELATIONSHIP WITH THE OTHER OF SAID TWO STATIONARY WALLS SOAS TO FORM A RESTRICTED PASSAGEWAY BETWEEN SAID ELONGATED GROOVE ANDSAID SLIT.